Integrated circuit devices, such as processors, microcontrollers, application specific integrated circuits (ASICs), programmable logic devices (PLDs), programmable logic arrays (PLAs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs), can include numerous types of discrete circuit components, including transistors, resistors, and capacitors, as well as other components or circuit structures. Device designers and manufacturers routinely attempt to increase the speed and performance of such integrated circuit devices while at the same time reducing die and/or package size and maintaining device reliability. However, the presence of hundreds of thousands or millions of closely-spaced transistors and other discrete components exhibiting sub-micron dimensions and operating at high clock rates inevitably causes the device to exhibit high power dissipation and heating.
High temperatures can damage or destroy integrated circuit components, and operation of an integrated circuit at a temperature above a certain level can be indicative of design or manufacturing defects in the device. Consequently, many systems, devices, and techniques exist for measuring and monitoring integrated circuit temperature.
FIG. 1 illustrates a simplified block diagram of prior art integrated circuitry temperature monitoring devices and techniques. In this example, the integrated circuit 100 (shown as an FPGA in the figure) includes a simple diode structure 105 fabricated on its die. The anode and cathode of diode 105 (shown here as corresponding to the base and the emitter of the pnp device) are bonded out to external pins of integrated circuit 100, which in turn are coupled to diode current source and sink pins of temperature sensor integrated circuit 110. Temperature sensor integrated circuit 110 typically measures the change in diode 105's base-emitter voltage (VBE) at two different operating points. For a bias current ratio of N:1, the difference between the two voltage measurements is given by:
  Δ  ⁢          ⁢      V    BE    ⁢  η  ⁢            k      ⁢                          ⁢      T        q    ⁢            ln      ⁡              [        N        ]              .  
With the measured value of ΔVBE, temperature sensor integrated circuit 110 can determine the temperature T of the diode from the constants k (Boltzmann's constant) and q (electron charge), as well as the known value of the bias current ration N. The only remaining parameter, η (the non-ideality factor of the process on which the diode was manufactured) can be specified using information from the device manufacturer. An example of temperature sensor integrated circuit 110 is the LM83 Triple-Diode Input and Local Digital Temperature Sensor with Two-Wire Interface from National Semiconductor Corporation. Numerous other similar devices will be well known to those having ordinary skill in the art. Once a device temperature is determined, it can be reported, logged, or compared to a threshold value. In the example illustrated, temperature sensor integrated circuit 110 compares the measured temperature to a threshold value, and signals some other device, e.g., hardware shutdown circuitry, when the measured value exceeds the threshold.
While the devices and techniques shown in FIG. 1 offer the advantages of relative simplicity and accuracy, they offer a number of disadvantages. For example, in order to reduce parasitic resistances in series with the diode 105, the diode is manufactured in such a way that it consumes a large area on the die of integrated circuit 100. Because die real estate can be very valuable, this often restricts implementation to one diode, and thus one measuring point, per die. Additionally, diode 105 typically needs to be located close to the edge of the die to further reduce parasitic effects in the signal from the device. Unfortunately, the edge of the die is not necessarily the best (or most representative) location to measure temperature, e.g., the center of the die is typically better. As illustrated, both the anode and cathode have to be bonded to dedicated pins of integrated circuit 100, thereby adding to packaging costs. Moreover, the temperature measurement system uses a specialized external device (circuit 110). Finally, additional parasitic effects can impact device signals because temperature sensor integrated circuit 110 is not connected directly into diode 105, but is instead connected through PCB traces, to package pins, through packaging, along bond wires to die bond pads.
Accordingly, it is desirable to have integrated circuit temperature measurement devices and techniques that reduce or eliminate many of the deficiencies of the prior art.